Oh, a lot; I get per-limb lean body mass, so now I know my right arm has a little less muscle than my left arm, so now I can integrate that in my training.

For my the body fat percentage is the most relevant part because now I know that I have a lot of room to lose weight 😅 

 I like this stuff too but the issue is being able to measure  it without them afterwards

e. g. per limb you need their fancy toys

Not too long though before proper diagnostic tools are cheap, wearable and hopefully (private) 

 Does it allow you to assess how much visceral (as opposed to subcutaneous) fat you have? 

 Yes it does. 

 You need a special machine that shoots radiation through you, like an x-ray. I think they look mostly at your long bones, femur, humerus. There may be some that look at your calcaneus(heel bone). Google it.